A 15-year-old boy has appeared in Perth Children's Court over the sexual assault of an 88-year-old woman in the Great Southern.

It is alleged the teenager stole from the woman and then assaulted her last Thursday.

The boy appeared in court today on multiple charges, including aggravated sexual assault and aggravated burglary.

The teen's lawyer applied successfully to have the case adjourned to obtain further legal advice.

The case was adjourned for two weeks after prosecutors said there was a significant chance of further charges.

The teenager was remanded in custody until his next court appearance in mid May.